What do you mean? Shouldn’t it go something like this: (syntax-parameterize ([current-defs (mutable-set)]) (match-define (sender x) 1) (reciever) x) ; => (syntax-parameterize ([current-defs (mutable-set #’(define x x3)]) (match-define x3 1) (reciever) x) ; => (syntax-parameterize ([current-defs (mutable-set #’(define x x3)]) (define x3 (match 1 [x3 x3])) (reciever) x) ; => (syntax-parameterize ([current-defs (mutable-set #’(define x x3)]) (define x3 (match 1 [x3 x3])) (define x x3) x)
The match-define form never defines “x” as anything, but the receiver should, right? On Aug 1, 2014, at 8:12 PM, J. Ian Johnson <i...@ccs.neu.edu> wrote: > Ah, okay, so... this macro expander you give is fundamentally flawed because > match-define does an initial parse (which uses the match expander) to get the > identifiers it is going to define. So, when you expand to x3 as the match > pattern, you end up returning x3 as one of the values that the match-define > -> define-values is going to define. It does not ever define "x" as anything > because that was just arbitrary syntax that was given to the match expander. > This x3 is x3 definition leads to a use-before-initialization error. > > Do you have a different example that doesn't fail in this way? > -Ian ____________________ Racket Users list: http://lists.racket-lang.org/users
